In order to understand the formative processes and textural change of anglesite from galena under natural sulfuric acid condition, chemical reaction of galena with sulfuric acid was experimentally examined. In the experiment, galena was sealed in the polypropylene bottle with sulfuric acid solution, and left for fixed duration in time. Three series of experiments, i.e., long term, rate analysis and solid textural analysis experiments, were carried out with changing temperature (30 to 170 °C), concentration of sulfuric acid (0.01 to 1 mol/l), duration (1 to 56 days) and state of galena (powder, grains or plastic crystals). The run products were filtered by 0.20 μm membrane filters, and the filtrated solution and residual solid were analyzed.
In the residual solid for all runs, the one and only identified reaction product is anglesite. In the long term experiment using powdered galena for 56 days, the amount of anglesite production increases with the increases of sulfuric acid concentration and temperature, which is well correlated with the equilibrium calculation results with considering oxygen contents in the bottle. The rate analysis experiment using powdered galena indicates that the amount of anglesite production increases with reaction time. Dissolution rate of galena for 1 day increases with the decrease of sulfuric acid concentration and the increase of temperature, in the range of 8.29×10^-9 mol・m^-2・s-¹ for the conditions of initial sulfuric acid 1 mol/l-110°C and 1.83×10^-8 mol・m^-2・s^-1 for 0.1mol/l-170°C. In the solid textural analysis experiment using grains or plastic crystals of galena, two types of anglesite occurrence are found, i.e., coarse euhedral crystals growing outside on galena surface and aggregates of fine grains which replace the initial galena crystal from surface. This differences would be explained by the degree of saturation for lead and sulfate ions under the microenvironment at the site of their formation. The random orientations of coarse euhedral crystals of anglesite on galena may be due to nonepitaxial growth. The increase of size of coarse euhedral crystals with time can well be explained by the Ostwald ripening.

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We experimentally investigated the fractionations and sedimentation characteristics of indium, gallium, arsenic and lead in acidic solutions. Sorption behaviors of In, Ga, As and Pb onto Fe and Al oxyhydroxides and iron-aluminum mixed hydroxide were strongly dependent on pH, and were considerably sensitive to acidic conditions, such as nitric acid, hydrochloric acid and sulfuric acid. Indium was preferentially adsorbed onto Fe oxyhydroxides and iron-aluminum mixed hydroxide mixture at pH > 3.5. Arsenic has large affinity for Fe oxyhydroxides and most arsenic was adsorbed at lower pH (pH < 2.5). Gallium has high affinity for Fe oxyhydroxides, iron-aluminum mixed hydroxide mixture and Al oxyhydroxides in that order at pH > 2.5. Lead has high affinity for Fe oxyhydroxides and iron-aluminum mixed hydroxide in that order at pH > 2.5. Their sorption behaviors were facilitated in by sulfate condition.
Hydroxides of iron and aluminum in aquatic systems significantly influence the distribution, mobility and bioavailability of trace elements. Experimental results predicted that fractionation among indium, gallium, arsenic and lead may be occurred in natural river condition due to their pH dependency and affinities to hydroxides of iron and aluminum.

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The 2011 earthquake off the Pacific coast of Tohoku and the following tsunami caused loss of a large number of lives, destruction of not only many private houses but also infrastructures, and the Fukushima I nuclear accidents, although disasters for the mineral and exploration world in Japan were not so serious. It is other sensational topics that gold prices have increased rapidly, and are higher than 1800 US$/oz in August, 2011, and that copper prices recorded the highest of 8966 $/t (LME) on November 11, 2010. Japanese mining, petroleum and trading companies and JOGMEC (Japan Oil, Gas and Metals National Corporation) continue their activities steadily, and get many fruitful results in exploration and development of mineral and energy resources, which have been carried out in these several years and decades. For example, Sumitomo Metal Mining Co., Ltd and Sumitomo Corporation have confirmed the presence of a gold, silver, and antimony mineralization zone in the Stone Boy project, Araska. Idemitsu Kosan Co., Ltd and JX Nippon Oil & Gas Exploration Corp. have been awarded independently and jointly many new exploration licences located in British and Norwegian North Sea, and conduct the exploration programs in some blocks as the operatores.

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